DESCRIPTION The aim of this program is to train postdoctoral fellows in mechanistic approaches (at the cellular and molecular levels) for investigating the role of environmental factors in mutagenesis and carcinogenesis. The major part of the training program consists of a research apprenticeship of postdoctoral trainees with one of 18 faculty preceptors (usually for three years). The proposal is to continue training a steady state level of 12 postdoctorals. The areas of research are concentrated on the basic mechanisms involved in tissue injury, mutagenesis and carcinogenesis, DNA damage and repair, chromosomal instability, DNA and protein structure, cytogenetic, cell cycle regulation, tissue remodeling, embryology, differentiation and development. This direct, laboratory based research training is supplemented by the following: seminars at LREH and other parts of UCSF; topical short courses given by some of the LREH faculty in the areas of Recombination, Radiation Biology, and DNA repair; journal clubs, a biweekly Research Conference for all trainees and preceptors; and the potential to take basic graduate level courses, as needed. M.D. trainees are required to attend two summer courses in Molecular Biology and Cell Biology offered as part of an introduction to research by the UCSF Molecular Medicine Program.